<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0px;
            padding: 0px;
        }
        .box{
            width: 5rem;
            height: 5rem;
            background-color: gold;
        }
    </style>
    <!-- 适配的JS文件，是我们自己写的 -->
    <!-- <script src="./js/flexible.js"></script> -->

    <!-- 淘宝团队，出了一个叫lib_flexible -->
    <script src="./js/lib_flexible.js"></script>
</head>
<body>
    <!-- 
        上盒子让屏幕一半
            750的屏: html的fs为75px      1rem = 75px          375px转rem 5rem
            375的屏：html的fs为37.5px    1rem = 37.5px         5rem
            320的屏：html的fs为32px      1rem = 32px           5rem
            414的屏：html的fs为41.4px    1rem = 41.4px         5rem
     -->
    <div class="box"></div>
</body>
</html>